Conventionally, in electric motor-driven refrigerant compressors that are used in heat pump equipment and refrigerating cycle equipment, torque from an electric motor is transmitted to a compressing mechanism by a crank shaft to compress a refrigerant gas using the compressing mechanism. The refrigerant gas is compressed by the compressing mechanism discharges into a sealed vessel, and moves from a lower space to an upper space relative to the electric motor through electric motor portion gas channels, and subsequently discharges to a refrigerant circuit outside the sealed vessel, but lubricating oil that is supplied to the compressing mechanism mixes with the refrigerant gas, and is discharged outside the sealed vessel. Conventionally, some problems have been that if the discharge rate of the oil that is removed to the refrigerant circuit increases, heat exchanger performance is reduced, and in addition if the amount of oil stored inside the sealed vessel is reduced, deterioration in reliability may arise due to lubrication failure.
In recent years, size-reducing developments in compressors, and conversion to alternative refrigerants (including natural refrigerants) that have a smaller environmental load have accelerated, and there is demand for oil separating techniques in the sealed vessel to be advanced. At the same time, since oil separating mechanisms inside the sealed vessel are complicated, and observational experiments also cannot be performed easily, there are many unexplained portions, and there are also many unsolved technical problems.
For example, refrigerant compressors have been disclosed in which are disposed as electric motor portion gas channels: a first gas channel that is constituted by a plurality of penetrating apertures (abbreviated to “rotor vents”) that communicate axially between upper and lower ends of a rotor; a second gas channel that is constituted by an air gap that is secured between a rotor outer circumferential surface and a stator inner circumferential surface and groove portions that are formed in a stator from openings of winding accommodating slots to an inner circumferential surface of the stator; and a third gas channel that is formed on an outer circumferential side of the windings of the stator inside the sealed vessel inner wall and that is constituted by a plurality of penetrating apertures that communicate axially between upper and lower ends of a motor, flow channel cross-sectional area of the rotor vents that constitute the first gas channel being greatest, wherein a disciform oil separating plate is fitted over a crank shaft so as to be tightly fitted, and the oil separating plate is held so as to be separated from rotor vent upper ends by a predetermined clearance (see Patent Literature 1, for example).
Rotary compressors have also been disclosed in which a counterweight is used to make oil that is discharged from a gas vent aperture collide with a colliding portion so as to form a large mass and flow back (see Patent Literature 2, for example).
High-pressure shell scroll compressors have also been disclosed in which refrigerant that is sucked in is compressed by a compressing mechanism that is disposed in an upper portion inside a sealed vessel, then allowed to descend to an oil pool on a floor of the sealed vessel, then raised through an electric motor gas channel from an electric motor lower space to an upper space, and high-pressure gas is discharged from a compressor discharge pipe, by rotation of a fan that is mounted to an upper portion of an electric motor rotor, to control refrigerant gas flow and also facilitate oil separation (see Patent Literature 3, for example).